Improvement in telephonic circuits



A.K.BATON.

Telephonio Circuit.

No. 222,476. Patented Dec. 9, I879.

WITNESSES: INVEN TOR: usm/lQmw ,1 R. Q- AMW' V I -FETERS, PMOTD-UTNOGRAPHER, WASHINGTON. D C,

UNITE STATES P TENT OFFICE.

ASAHEL K. EATON, OF BROOKLYN, NEWV YORK.

IMPROVEMENT lN TELEPHONIC CIRCUITS.

Specification forming part of Letters Patent No. 222,476, dated December 9, 1879; application filed November 18, 1878.

To all whom it may concern:

Be it known that I, A. K. EATON, of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Telephonic Circuit for Electrical Purposes, of which the following is aspecification, reference being made to the accompanying drawin gs, making part of the same.

This invention consists of a telephonic circuit composed of an insulated metallic cond uctin g-wire inclosed within a tube of lead, tin, or other suitable metal, the metallic inclosingtube being used as the return-circuit, by which the well-known inductive efi'ects of neighboring wires on telephone-lines are neutralized and prevented from interfering with the intelligible transmission otarticulate sounds.

The compound wire or conductor employed by me for this purpose consists of a central core of wire, copper, steel, or any equivalent metal suitable for the transmission of the electric current, fully inclosed by a sheathing of lead, tin, or other ductile metal, the two being perfectlyinsulated with reference to each other.

A simple form of the compound wire consists of an iron wire of the desired size covered with cotton in the usual way, and the covering saturated with parafline, wax, caoutchouc, or other electrically non -conducting substance.

The prepared wire is passed through a comparatively-short piece of large pipe, and this pipe is gradually reduced in diameter and increased in length by passing it through a series of dies or rolls until it closes down upon the central wire and forms a compound conductor of the required size.

The serious effects of induction upon ordinary telephone-lines run. in the vicinity of any batterycurrent line are well known.

A telephonic circuit of this compound wire obviates the difficulty entirely, since a com plete metallic circuit, the wires of which are arranged parallel to each other in the neighborhood of wires from which disturbing inductive effects proceed, neutralizes the induced currents by causing them to act in opposite directions through the coils of the telephone.

In the drawings is shown an embodiment of the invention. Figure l is a plan, and Fig. 2 a longitudinal section through the compound wire and its connections.

A is the central-wire conductor; G, the insulating material; B, the incasing lead tube or sheathing; B, the return-circuit wire.

A compound wire of this construction employed as a telephonic circuitin the manner described has special advantages over two ordinary wires armnged parallel to one another, in that no care is required in putting up the line to secure parallelism between the wires. nor need any special attention be paid to the position of the iiulucing-wires with relation to the telephonic circuit, since, no matter what position they n'iay have with relation to the compound conductor employed by me, the in duced "currents set up in the central wire and the metallic sheath will be in substance the same.

Having thus described and illustrated my invention, I do not claim, broadly, a telephonic circuit consisting of parallel wires arranged in close proximity to each other; but

I claim A telephoniccircuit for avoiding or neutral izing the induction efi'ects from neighboring wires, in which the exterior metallic covering of an insulated conductor is utilized for conveying back the return or earth current.

ASAHEL K. EATON.

\Vitnesses FRANK W. STONE, Tnos. O. SEYMOUR. 

